Waveform shaping filters that can control a time constant have been used to narrow a pulse width of a signal pulse that is output in a state where the pulse width is expanded. As a conventional waveform shaping filter, one that samples a trailing edge of the signal pulse, detects occurrence of an overshoot (or an undershoot) using a sampled value, and controls the time constant based on a detection result has been proposed.
However, there is a problem that this waveform shaping filter requires a sampling circuit for sampling the trailing edge of the signal pulse, a control circuit for generating the sampling pulse, an AD converter for AD-converting the signal pulse at a high speed, and the like, and thus a circuit scale is increased.